Anti-icing gasoline



United States ANTI-ICING GASOLINE William E. Lovett, Scotch Plains, Raymond W. Walker, Union, and John M. Jordan, Plainfield, N.J., assignors to Esso Research and Engineering Company, a corpo- The present invention relates 'to improved fuels for use in spark-ignition internal combustion engines and more particularly, relates to improved gasolines inhibited against carburetor icing during cool, humid weather by the incorporation therein of minor amounts of a synergistic 'mixture of a low boiling aliphatic alcohol and a primary "amino -alkanol.

The problem of carburetor icing and the engine power losses and stalling which result therefrom is *not a new one. Operators of automotive, aviation, marine and stationary gasoline engines, particularly those in the colder areas of the United States, have long been familiar with the problem. Tests and surveys have shown that most engines are subject to carburetor icing when the atr'nos: pher'ic temperature ranges from about 30 to about 60 F. "and when the relative humidity is in excess of about 65%. Such icing is not confined to any particulan't ype of engine or to any particular type of carburetor. When a gasoline engine is first started, the engine carburetorfils immediately chilled to a temperature considerably below the atmospheric temperature due to the refrigerating effect of the vaporizing gasoline. This reduced carburetor tethperature, often as much as 50 F. below the atmospheric temperature, persists beyond the warm-up period for the rest of the engine because of the external position of the carburetor and the poor heat transfer to it. 'On a humid day, moisture in the air entering the carburetor condenses and freezeson the throttle plate and the carburetor walls 3 adjacent thereto. Such freezing occurs most readily duralso more severe in engines having the venturi tube in; sulated from the carburetor body. Many gasoline engines are equipped. with carburetors having these features. In. recent years the problem of carburetor icing and enginestalling-hasbecome more severe, particularly with respect to automobile engines. Most late model cars have automatic throttles and therefore drivers are no .longerrable to increase the engine idling speed during the warm-up period in order to prevent stalling; More over, modern automobileshaving automatic transmising the warm-up period. The fastest idling speed which can '-be tolerated without creeping of thecar is often too low to prevent stalling of the engine. m e I Another taetorqwhich has made the problem of care lresen't day fuels are considerably more volatile than this. ASTMsp "'ifications now permit a maximum 50% distillation point of 284 and most commercial "gasolines have 50% distillation jpoints somewhat below the allowable ASTM hiaxnriurn. These highly volatile modern .ga'soline's gives r'i'set'o carburetor icin'g and stalling difliculties much irr'o'r'e frequently thanth'e older, less volatile fuels.

The .present invention provides an improved class of gasolines inhibited against carburetor icing and consequent stalling by the incorporation therein of a mixture of a low boiling aliphaticalcohol and a primary aminoalkanol. In accordance with the invention, it has nowbee'n 'found that these materials in combination exhibit a synergistic elfect and give considerably greater protection against carburetor icing than either component alone. considerably lower concentrations are thus made possible by the invention. In addition, the presence of the low boiling aliphatic alcohol considerably improves the solubility of the :primary amino alkanol in gasoline at low temperatures and reduces the water extractability of .the primary amino alkanol. This results :in a fuel which is more stable than those employing the primary amino alkanol as the sole anti-icing-agent. The addit-ives of the invention have the additional advantage in that they prevent rusting and corrosion which often takes place due to the presence of small quantities of water in gasoline.

The primary amino a lk'anols which are used in the igasolines of the present invention have the generic forwhere -R is an alkyl "radical having from 1 to 3 carbon atorhs, it is zer'otb'bne and R is selected from the group consisting of hydrogen aria alkyl groups containing from l "to 2 carbon atoms; wherein {the amino group is a primary amino group attached to a tertiary carbon atom; and wherein the total number of carbon atoms ranges from about 4 to about 9, preferably from about 4 to about 6. irh'e' eemps "'ds rep'r'esehted by this term n ls are primary-amino, te y alkyl ca r'bihols. The allryl' groups can be inthyl,etl'iyl, propy'l isopropyl g'rlo ps. particularly preferred primary amino alkanol for use in accordance with the invention is 2-amino-2-methyl-lpropanol. I r e The low boiling anchors employed in the fuels bf th'e' invention are'thbs'e 'Cbh'tiiiiihgfibir'i 'Zto 5 carbon atoms per Insecure aha in'c'l de "thahbl, pfop'aliol, isoprlopanol,

phatic alcohol are employed in the fuels of the invention in concentrations such that the fuels contain from about 0.001 to about 0.4% by volume of the primary amino alcohol. .wG'oncentnations ofgfrom about 0.05fi'to about 0.1%ibyjv'olume:of'primaryTamino alkanol'andc'oncensions have idling speeds WhlCh are rather critical durburetor ieing more serious in recent yearsis thevolatility of the gasolines n'owmarketed. Tests have shown jthatla wholly hydrocarbon fuel having volatilitysuch thatthe ASTM 50% distillation p t by method-D 35 is above ut F0?" "is not edifice trations-ofvabout =0.7-5 to.abqut"l.25%'by 'volurneiof the amino alkanol ranges from about 40 ml "about '5' to Gasolin'es 'as contemplated for use in. iaocordance w thepresent invention have beenxdefin'ed broadly were American Socitydo'i Testing 'Mater'ialsras ffcomplex.

stalling du 'ngwaffiii-up. tures composed almost ehtirely fi ofdelatively" Zola e T 3 I hydrocarbons which vary widely in their chemical and physical properties. Such gasolines are derived from petroleum by a variety of refining processesincluding fractional distillation, catalytic cracking, hydroforming, alkylation, polymerization, solvent extraction .and the like. They include aromatics, naphthenes, olefins, paraffins and sometimes diolefins. They maybe used as fuels for ayiation engines, marine engines and stationary engines. Gasoline normally boils between about 80 F. and about 450 F. when tested by ASTM method D-86. Its vapor pressure by ASTM method D-323 varies from about 6 to about 15 pounds per square inch or higher at 100 F., depending on the particular season of the year during which it is to beused. The additive materials of the invention are'of particular application to gasolines having vapor pressures in the upper part of this range, i.e. between 9 and 15 pounds'per square inch. The gasolines in which the additive materials of the invention are used may have octane ratings ranging from about 83 up to about 104 or higher. Such gasolines normally contain at least 2 cc. of tetraethyl lead per gallon and a halohydrocarbon scavenger agent in concentrations of about 1.0 to 2.0 theories.

The gasolines in which the additive materials of the invention are incorporated may also contain other addi- 'tive materials. Examples of such additive materials include solvent oils'consisting of hydrocarbon mixtures having a Saybolt viscosity at 100 F. not above 450 seconds, a 50% distillation point above about 350 F. at 10 millimeters of mercury pressure, and an API gravity between about 18 and 28; corrosion inhibitors such as Santolene C, which is a phosphorus-containing dimer of linoleic acid, amines and amine phosphates and nitrites; gum inhibitors such as N,N' disecondary butyl p-phenylene diamine, 2,4-dimethyl-6-tertiary butyl phenol and 2,6-ditertiary butyl-4-methylphenol; dyes such as l,4-diisopro pyl aminoanthraquinone and p-dimethyl aminoazobenzene; dye stabilizers such as ethylene diamine; and similar additive materials commonly used in gasolines. The gasolines of the invention will, however, comprise at least 95% by weight of hydrocarbons.

The invention can be more fully understood by reference to data set forth in the following examples.

EXAMPLE 1 Tests were carried out todetermine the carburetor icing characteristics of a premium grade leaded motor gasoline with and without the additive materials of the invention. The gasoline had the following inspections:

Samples of .this gasoline were blended with small amounts of a low boiling aliphatic alcohol, .a primary amino alkanol, and mixtures'of the low boiling alcohol and alkanol. 1 These samples were then tested in a 1956 Plymouth engine by starting the engine, operating it for a period of 30- seconds at 1500 revolutions per minute; and then permitting the engine to idle for 15 seconds.

This procedure was repeated25 times, the engine being cold at the beginning of each test series. The number of stallswhich occurred in each series of tests was noted and taken'as an indicationlof thecarburetor icing characteristics of thefuel being tested.l The data were obtained at V an atmospheric temperature of 40. F. and 'at 100% 'rela:

tive humidity. The .resultsj-ofthis test are shown in..the

following table.

Table ANTI-ICING EFFECT OF ADDIIIVES Average number Fuel oi stalls in 25 cycles 1 Base gasoline 2 18 Base gasoline plus 1.0% isopropanol.-. 14 Base gasoline plus 2.0% isopropanol 7. 6 Base gasoline plus 0.05% Z-amino-2-methyl-1-propanol 11 Base gasoline plus 0.1% 2-amino-2-methyl-l-prnpanol 7.8 Base gasoline plus 0.05% 2-amino-2-methyl-1-propanol plus a 1.0% 1sopropanol (expected) 7 Base gasoline plus 0.05%

1.0% isopropanol (found) 5 1 Data were obtained with a 1956 Plymouth test car operated at a temperature of 40 F. and 100% relative humidity.

2 Base gasoline was a premium Winter grade gasoline having a Reid vapor pressure of 13.5 psi. and an ASTM 50% distillation point of 190 F.

EXAMPLE 2 Primary amino alkanols have excellent anti-icing properties. ,Their physical properties, however, limit their usefulness as gasoline additive agents. They have extremely low solubility in gasoline at the temperatures which are often encountered in aviation fuel tanks at high altitudes and in automobile gasoline tanks during the winter. In order to demonstrate the improved properties which result when such primary amino alkanols are used in conjunction with low molecular weight aliphatic alcohols, a series of tests was carried out in which the solubility of 2-amino-2-methyl-l-propanol in gasoline containing various amounts of isopropanol was determined at '20 F. The results of these tests are summarized in Table II below.

Table II EFFECT OF LOW MOLECULAR WEIGHT ALCOHOLS UPON SOLUBILITY OF PRIMARY AMINO ALCOHOL Solubility of 2-aminn-2- Fuel methyl-1- propanol in fuel-at 20 F., percent Basegasoline 0.01 Bnse gasoline plus 0.6 7 isopropanol 0. 05 Base gasoline plus 0.81 isopropanol--. 0. 10 Base gasoline plus 1.0% isopropanol 0. 30

" 1 Base gasoline was a premium winter grade gasoline having 'a Reid vapor pressure of 13.5 p.s.i. and an ASTM 50% distillation point of 190 F.

It can be seen from Table II that while the solubility of Z-amino-Z-methyl-l-propanol in gasoline isonly 001 volume percent-at '20 F., the presence of 1% isopropanol increases solublity of the primary amino alkanol to 0.3%. This increase in solubility at low temperature is'significant because it provides a method for preventing the separation of the primary amino alkanol fromjthe gasoline at 'a'low'temperature and thus assures that the anti-icing properties contributed by the alkanol are not lost at high altitudes or during severe winter weather. Ethanol and other low boiling aliphatic alcohols have been found. to affect the solubility of the primary amino alkanol in the manner shown for isopropanol in the above table a EXAMPLE 3 ;Becaus the water solubility of primary amino alkanols, they are often extracted from gasolines stored;

for prolonged periods. In accordance with the invention it has been found that in addition to the benefits shown above, the presence of a low boiling aliphatic alcohol decreases the water extractability of the primary amino alkanols. Tests were carried out in which gasolines containing 2-amino-2-methy1-l-propanol were mixed with water, in the presence and in the absence of isopropanol, and the distribution of the primary amino alkanol between the water and the gasoline phases was determined. The tests were carried out at temperatures of from 70 to 80 F. The data obtained are shown in Table III below. These tests were intentionally more severe than the conditions that would normally be encountered in commercial storage and use of gasoline.

Table III EFFECT OF LOW MOLECULAR WEIGHT ALGOHOLS UPON WATER EXTRACTABILITY OF PRIMARY AMINO ALKA- NOLS FROM GASOLINE 2-amlno-2- 2-amino-2- Equilimethyl-L methyl-lbrium Conpropenolin propanolin stant-Eq. Fuel asoline water cone. in

p ase,vol. phase,vol. water/e11. Percent Percent cone. in gasoline Base gasoline l 0. 05 34 680 Base gasoline+0.75 percent ispropanol..-- 0. O 24 480 Base gasoline 1 0. 1 58 580 Base gasoline+0.75 vol. percent isopropanol 0.1 44 440 To demonstrate the rust inhibiting efiect of the additive compositions of the invention, metallic strips were suspended in a gasoline similar to that employed in Example 1 containing a minor amount of water. To a sample of the same gasoline a very small amount of a mixture of isopropanol and Z-amino-Z-methyl-l-propanol was added and a similar metal strip was suspended in 1 Base gasoline was a premium winter grade gasoline having a Reid vapor pressure of 13.5 p.s.i. and an ASTM distillation point of 190 F.

The data of Table IV show that the additive materials of the invention are quite effective for inhibiting rust as well as for reducing carburetor icing.

EXAMPLE 5 An anti-stalling gasoline in accordance with the invention has a Reid vapor pressure or" 9 p.s.i. and an ASTM 50% distillation point of 210 F. and contains 2.0% ethanol, 0.3% 2-amino-2-methyl-propano'l-1, 3 cc./gal. of tetraethyl lead, 1.0 theories of ethylene dichloride, 0.5 theories of ethylene dibromide, 1.0% of a light neutral solvent oil having a Saybolt viscosity at F. of 380 seconds and 15 pounds of N,N',-disecondary butyl pphenylene diamine per thousand barrels.

What is claimed is:

A gasoline to which has been added about 0.4 to about 2.5 vol. percent of isopropanol and about 0.001 to about 0.4 vol. percent of 2-amind-2-methyl-1-propano1.

References Cited in the file of this patent UNITED STATES PATENTS 2,579,692 Neudeck Dec. 25, 1951 2,706,677 Duncan et a1. Apr. 19, 1955 2,840,461 Duncan et al. June 24, 1958 2,872,303 Donlan Feb. 13, 1959 FOREIGN PATENTS 782,833 Great Britain Sept. 11, 1957 1,007,557 Germany May 2, 1957 

